This invention relates generally to an image forming apparatus, and especially to a device for collecting toner waste from a photosensitive member of the image forming apparatus.
In an apparatus for forming images using a combination of an electrophotographic process and an optical signal generator, (e.g., a laser beam printer or liquid crystal shutter (LCS) printer), an image is formed on a photosensitive member which is then coated with toner. A portion of the toner coated image is then transferred to a recording medium. The non-transferred portion of the toner coated image remaining on the photosensitive member (hereinafter referred to as toner waste) is unsuitable for reuse and must be scraped off the photosensitive member and allowed to accumulate within a container.
Toner waste has a tendency to agglomerate. Such agglomeration near the entrance to the container can prevent additional toner waste from being deposited in the container. Toner waste if not deposited in the container, can settle within the apparatus on various components and thus adversely affect and deteriorate performance of the apparatus. It also increases the frequency of removing the container. Having to empty toner waste from the apparatus before the container is full is also undesirable.
In order to circumvent the problem of toner waste agglomeration, toner waste can be deposited into the container using a spiral carrier method disclosed in Japanese Patent Laid-Open Application No. 56-57076. Moreover, the spiral carrier method suffers from the inherent drawback of accumulating toner in a conical pile like fashion. Consequently, the volume of the container needs to be significantly larger with substantial volume going unused.
One possible solution for overcoming this accumulated conical pile of toner waste is to vibrate or shake the toner waste so as to flatten the pile. Moreover, the oozing and splashing of toner associated with such vibration or shaking as well as noise are undesirable and generally unacceptable.
Another drawback in the prior art relates to the need to alert a user that the container of toner waste needs to be emptied. A proposed solution involves activating a microswitch or other equivalent based on the weight of the toner waste. This solution is considered unreliable. Small amounts of toner waste deposited on the contact points of the microswitch can cause contact failure. Another proposed solution counts the number of revolutions made by the photosensitive member. Generally, each time the photosensitive member completes a revolution approximately 30-40% of the toner coated image is scraped off the photosensitive member and deposited into the container. Therefore, counting the number of completed revolutions of the photosensitive member should presumably indicate when the container is full of toner waste. The exact amount of toner waste is never determined in this latter proposed solution. Therefore, unless an unacceptably low number of revolutions is used as the threshold to trigger the alarm, toner waste can overflow from the container before the alarm is triggered.
Conventional image forming apparatus also splashes and/or oozes toner waste from the container following completion of the copying or printing cycle.
Accordingly, it is desirable to provide a cleaning device which overcomes the problems of toner waste agglomeration without having to increase the size of the container. It is also desirable to provide a toner cleaning device which fully utilizes the volumetric interior of the container for storing toner waste and which prevents splashing and oozing of toner waste following completion of the printing or copying cycle. It is also desirable to provide a cleaning device which alerts a user of the need to empty the container before the toner waste overflows and yet is far smaller in size than cleaning devices presently available.